Natalie Portman steps forth into the unknown in this sci-fi horror thriller. Portman plays Lena, a biologist and former soldier whose husband Kane (Oscar Isaac) has vanished under mysterious circumstances. Lena learns that Kane went on a mission into ‘the Shimmer’, an otherworldly anomaly. Within the Shimmer lie all manner of mutant flora and fauna, the structure of every living thing in its boundaries transformed by a meteor that hit a lighthouse three years earlier.

Lena volunteers to join an expedition into the Shimmer, with the knowledge that none who have entered before have ever left. Psychologist Dr. Ventress (Jennifer Jason Leigh) leads the team, which also comprises paramedic Anya Thorensen (Gina Rodriguez), physicist Josie Radek (Tessa Thompson), and surveyor and geologist Cassie Sheppard (Tuva Nuvotny). The five women venture into the Shimmer, attempting to decipher its enigma and, more importantly, emerge alive.

Annihilation is based on the novel of the same name by Jeff VanderMeer. The film was adapted for the screen and directed by Alex Garland, who made his directorial debut with the much buzzed-about sci-fi drama Ex Machina. Garland decided not to re-read the book, instead adapting the material as “like a dream of the book”.

There was a degree of intrigue surrounding Annihilation and it is clearly a film that was intended to be seen on the big screen, so it’s a bit of a shame that while it received a theatrical release in the U.S. and China, it is being streamed on Netflix everywhere else. It seems that Paramount financier David Ellison wanted the film reshot after poor test screening results, deeming it “too intellectual”. Director Garland insisted on keeping the film the way it is and was backed by producer Scott Rudin. Paramount eventually made a deal to let Netflix handle international distribution.

With that background out of the way, it’s easy to see why Annihilation might not win over mass audiences, but the very things that set it apart from typical commercial films also make it interesting. Annihilation is a movie that will mess with your head, and if challenging, cerebral sci-fi is what you’re looking for, you’ll find that and then some here.

In Annihilation, what’s scary is also beautiful. The Shimmer is a world in which lots of things have gone wrong — or has everything gone right, and it’s the world outside that’s out of order? Annihilation delves into some heady themes but has the visual invention to hold our interest as it burrows ever further into the madness.

With echoes of H.P. Lovecraft, the works of John Carpenter, Andrei Tarkovsky and Stanley Kubrick, Annihilation is deliberately opaque and vague, but is tense enough to reel the viewer in. Cinematographer Rob Hardy plays with the light within the Shimmer, rendering everything ethereal but slightly menacing. The effect, when combined with other atmospherics including the music by Geoff Barrow and Ben Salisbury, creates a beguiling yet disorienting world that is truly alien.

Annihilation isn’t all highfalutin ponderousness: there is a healthy number of visceral genre thrills, including sequences when our characters get chased by monsters like an albino alligator with shark teeth. There is one truly stomach-turning moment of gory body horror, but Annihilation gets under one’s skin with psychological trickery rather than overt grossness. Just like the characters, we’re questioning everything we see. Garland masterfully generates a sense of being sure of nothing except the danger.

It’s worth noting that the film’s main cast is all female. Each of the five characters who go on the expedition are distinct enough from each other and while there isn’t a great deal of development for everyone, there’s sufficient information conveyed about each character that we’re invested in them as a group.

Lena is competent and intelligent but haunted, and Portman portrays the character with sensitivity. She’s somewhat detached from the world, as if she’s lost a piece of herself since the disappearance of her husband. Lena is flawed and difficult to pin down. We see Lena fight battles internal and external, calling on her wits and determination to survive an overwhelming, perplexing ordeal.

Jennifer Jason Leigh is severe and guarded as Dr. Ventress, the authority figure who’s hiding something. We’ve seen Tessa Thompson play badass and assured, so it’s interesting to see her play withdrawn and insecure. Gina Rodriguez is a lively presence who also brings a degree of unpredictability to the table. Of the main cast, Tuva Nuvotny is the blandest, and a scene in which she tells Lena about the background of each team member feels a little on the nose.

For all its trippiness and immersive atmospherics, Annihilation makes several missteps. While the framing device set after the events of the bulk of the film is ostensibly to contextualise the flashbacks, it also means that we know at least some of the outcome of the expedition. There are moments when the film feels like it’s being ambiguous and confusing for the sake of it, but it never feels lazy while doing so.

Annihilation is an intense, thrilling and deeply creepy slice of sci-fi horror that’s different from typical genre fare. Garland continues to show promise as a genre director with an exciting voice, and many spirited discussions about the minutiae of the film and what it all means are bound to ensue. Step into the Shimmer; it’s a wild ride.